Modernized automatic vending machine or gaming machine or the like capable of operating with a bill in addition to the previously known coin or token is increasing recently. Though these machines are equipped with bill validators, machines served in unattended environment must have functions to prevent various fraudulent or criminal activities other than validation/discrimination of paper currency.
A typical fraudulent activity is to retrieve a bill by pulling a string or a tape attached to the bill out of the machine after vending goods or services. To countermeasure such “stringing” activity a conventional bill validator is typically disposed with a block gate secured rotatably in a pathway to prevent bills from being retrieved.
Now, a conventional bill validator is described with reference to the drawings. FIG. 9 shows a cross-sectional view of a structure of a conventional bill validator. Bill inlet 1 is coupled to pathway 2 provided with first transportation portion 3 and second transportation portion 4 as shown. Rubber rollers are adopted for all of the transportation means in this example. Magnetic sensor 5 and first optical sensors 6a and 6b are mounted on pathway 2 for the bill validation. Outlet 7 is located at an end of pathway that extends to a bill storage box, and anti-stringing block 9 secured rotatably with respect to supporting point 8 on its one end while extends to the pathway on its another end is provided between validation portion 5, 6a, 6b and second transportation portion 4.
Now, movements of a conventional bill validator are described. A bill detector (not shown) disposed at inlet 1 detects a bill inserting, and sends signals to controller (not shown) to drive first transportation portion 3 and second transportation portion 4 to transport the bill along pathway 2. Scanning the bill to obtain test data during the transportation along pathway 2, magnetic sensor 5 and first optical sensor 6a, 6b compare the data with data of valid bills taken previously. If disagreed to accept first transportation portion 3 and second transportation portion 4 rotate in a reverse direction to return the bill to inlet 1, and if agreed the bill is forwarded further.
Leading edge of the bill transported to pathway 2 lifts anti-stringing block 9 and leave the situation kept unchanged until the rear edge of the bill passes anti-stringing block 9. Anti-stringing block 9 extends in pathway 2 after the rear edge of the bill has passed anti-stringing block 9 to block a back flow of the bill. Therefore, a fraudulent activity to retrieve a bill by pulling a string or a tape attached to the bill out of the validator after vending goods or services would be blocked by the blocking of anti-stringing block 9.
Though such a known art as anti-stringing block 9 is an effective measure against fraudulence using bills only, but a perfect measure has been difficult for other fraudulence to retrieve bills once validated as authentic out of validator with small materials of metal or paper used together with the strings to lift anti-stringing block 9 from the pathway except an introduction of a path blocking apparatus at the end of bill validator that can guarantee to block the return of the bill.
U.S. Pat. No. 4,513,439 discloses an example of path blocking apparatus for such purposes in which approximately drum shaped body having a rectangular slot for passing bill is rotated to prevent bill from being retrieved. But the problem is that the validator including the drum shaped body becomes large and the power consumed in the driving apparatus increases.